1. Field of the Invention
The present invention relates to a portable cutting tool, such as a portable electric circular saw, on which a parallel ruler can be mounted.
2. Description of the Related Art
A conventional example of the portable electric circular saw as a form of the portable cutting tool is shown in FIGS. 14 and 15. In addition, FIG. 14 is a front view of a conventional electric circular saw, and FIG. 15 is a plan view of the conventional electric circular saw.
In a portable electric circular saw 11 shown in FIGS. 14 and 15, reference numeral 1 denotes abase, and reference numeral 2 denotes a circular saw body that can be rotated away from the base 1 about a supporting shaft 3 with respect to the base 1, can be adjusted in cutting length of a material to be cut, and can cut the material obliquely by the saw blade 4 inclined with respect to the material, rotating about a tilt shaft (not shown). In this case, the circular saw body 2 has a disc-like saw blade 4 for cutting a material (not shown) to be cut, such as a plate material, and a motor (not shown) as a driving source for rotating the saw blade 4.
A saw cover 8 is attached to a cover of a gear box 6 so as to cover the top of the saw blade 4, and a protective cover 9 is attached to the bottom of the saw blade 4 so as to expose a portion of the saw blade. In addition, the motor is housed in the motor housing 5, and its driving torque is reduced by a reduction gear (not shown) housed in the gear box 6 and is transmitted to a rotary shaft 7 of the saw blade 4 to rotate the saw blade 4 at a predetermined speed.
Therefore, as an operator forwardly pushes out a handle 10 with the base 1 placed on a material (not shown) to be cut while the saw blade 4 is driven to rotate as described above, the portable electric circular saw 11 cuts the material to be cut, by the saw blade 4 while it advances in a direction indicated by an arrow A in FIG. 15. In this case, it is difficult to accurately cut the material to be cut due to a gap between the handle 10 and the saw blade 4, along a cutting direction A in FIG. 15. Thus, a parallel ruler 12 is often used as shown in FIG. 16 so as to accurately guide the material along the cutting direction A (for example, see JP-A-6-312402).
FIG. 16 is a plan view of the conventional portable electric circular saw 11 on which the parallel ruler 12 is mounted. In the portable electric cutting circular saw 11 shown, a front guide bar 13 and a rear guide bar 14 are inserted through a front insertion hole 15 and a rear insertion hole 16, respectively, formed in front and rear portions (in upper and rear portions in FIG. 16) of the base 1, so that they are slidable in a right-and-left direction (a direction orthogonal to the cutting direction A) and parallel to each other. The guide bars 13, 14 are respectively fixed to the base 1 with a first fixing screw 17 and a rear fixing screw 18. Also, the parallel ruler 12 is attached parallel to an end face of the saw blade 4 between ends of both guide bars 13, 14 protruding from the base 1.
Here, the cutting operation by means of the portable electric circular saw 11 shown in FIG. 16 is shown in FIG. 17. Specifically, FIG. 17 is a partial view as seen in a direction indicated by an arrow X (a view showing only a portion needed for explanation of the cutting operation) in FIG. 16. In the cutting operation, as shown in the figure, the parallel ruler 12 is caused to slide along a side P1 of the material P to be cut, so that the cutting direction of the material P to be cut by the saw blade 4 can be surely guided. Also, chips are generated during cutting of a material P to be cut, and the chips are scattered in a direction indicated by an arrow B by the wind induced by rotation of the saw blade 4.
On the other hand, as one kind of cutting operation of a material to be cut, there is an operation to cut a floor material at the edge of a wall. In this operation, a circular saw (hereinafter, referred to as a wall-edge cutting circular saw) shown in FIGS. 18 and 19 is frequently used (see Japanese Patent No. 2933196). In addition, FIG. 18 is a plan view of a wall-edge cutting circular saw, and FIG. 19 is a plan view showing a procedure of the wall-edge cutting circular saw.
As shown in FIG. 19, when a floor material P at the wall edge is cut using the wall-edge cutting circular saw 11′, the floor material P can be cut along the wall edge, in a state in which the circular saw body is rotated about the tilt shaft 3 and tilted at a predetermined angle with respect to the base 1, and the saw blade 4 protrudes outward from the side 1a of the base 1. If the wall-edge cutting circular saw 11′ can cut the floor material P along the wall edge, the side 1a of the base 1 along the direction of the wall edge, and side 1a of the base 1 along the direction of the wall edge is shortened in order to avoid that the side 1a of the base 1 along the direction of the wall edge interferes with a wall W.
Here, an example in which the parallel ruler 12 is mounted on the wall-edge cutting circular saw 11′ and the wall-edge cutting circular saw 11′ is used for cutting other than the wall-edge cutting is shown in FIG. 20. Even in this case, chips are generated during cutting of the material P to be cut, and the chips are scattered in a direction indicated by an arrow B, by the wind induced by the rotation of the saw blade 4.
In the above-described portable electric circular saw 11 and wall-edge cutting circular saw 11′, even in any usage patterns, chips generated during cutting operation are scattered to the surroundings and stuck on the operator, or deteriorate the visibility in cutting spots, therefore, the operation efficiency may be deteriorated.